Fine structure of shear bands formed during hot deformation of two austenitic steels

Cizek, P., Bai, F., Rainforth, W.M. and Beynon, J.H. 2004, Fine structure of shear bands formed during hot deformation of two austenitic steels, Materials transactions, vol. 45, no. 7, pp. 2157-2164.


Title Fine structure of shear bands formed during hot deformation of two austenitic steels
Author(s) Cizek, P.
Bai, F.
Rainforth, W.M.
Beynon, J.H.
Journal name Materials transactions
Volume number 45
Issue number 7
Start page 2157
End page 2164
Publisher Japan Institute of Metals
Place of publication Sendai , Japan
Publication date 2004
ISSN 0916-1821
1347-5320
Summary Shear bands formed during both cold and hot plastic deformation have been linked with several proposed mechanisms for the formation of ultrafine grains. The aim of the present work was to undertake a detailed investigation of the microstructural and crystallographic characteristics of the shear bands formed during hot deformation of a 22Cr-19Ni-3Mo (mass%) austenitic stainless steel and a Fe-30 mass%Ni based austenitic model alloy. These alloys were subjected to deformation in torsion and plane strain compression (PSC), respectively, at temperatures of 900°C and 950°C and strain rates of 0.7s-1 and 10s-1, respectively. Transmission electron microscopy and electron backscatter diffraction in conjunction with scanning electron microscopy were employed in the investigation. It has been observed that shear bands already started to form at moderate strains in a matrix of pre-existing microbands and were composed of fine, slightly elongated subgrains (fragments). These bands propagated along a similar macroscopic path and the subgrains, present within their substructure, were rotated relative to the surrounding matrix about axes approximately parallel to the sample radial and transverse directions for deformation in torsion and PSC, respectively. The subgrain boundaries were largely observed to be non-crystallographic, suggesting that the subgrains generally formed via multiple slip processes. Shear bands appeared to form through a co-operative nucleation of originally isolated subgrains that gradually interconnected with the others to form long, thin bands that subsequently thickened via the formation of new subgrains. The observed small dimensions of the subgrains present within shear bands and their large misorientations clearly indicate that these subgrains can serve as potent nucleation sites for the formation of ultrafine grain structures during both subsequent recrystallisation, as observed during the present PSC experiments, and phase transformation.
Language eng
Field of Research 091207 Metals and Alloy Materials
HERDC Research category C1.1 Refereed article in a scholarly journal
Persistent URL http://hdl.handle.net/10536/DRO/DU:30025770

Document type: Journal Article
Collection: Centre for Material and Fibre Innovation
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